In conventional boat lifts, a boat or other type of watercraft is accommodated on a platform which is typically raised and lowered by a winch and cable mechanism. A wide variety of such lifts are known. However, virtually all exhibit one or more of a number of disadvantages.
The lift platform is usually raised by a motor or hand crank. To return the vessel to the water, the platform is lowered with the assistance of gravity. Most known boat lifts employ either a gear reduction or a separate brake mechanism to slow the descent of the platform. Such mechanisms contribute significantly to the complexity and expense of the boat lift.
Additionally, many standard cable-operated lift platforms experience problems with buoyancy. In order to properly lower the boat into the water, the hull of the vessel must be partially submerged. Most boat lift platforms employ structural components (e.g. cradle beams, bunk boards, etc.) that are composed of buoyant or low density materials such as wood or lightweight aluminum. Consequently, as the lift platform is lowered by gravity it tends to float on the water. This can prevent the hull of the watercraft from being properly submerged. Moreover, when the platform suddenly engages the water and floats, the cables may continue to unwind from the spool of the winch. This can cause the cables to unravel and tangle. Operation of the boat lift may be disrupted and costly, time consuming repairs may be required.
Standard cable driven boat lifts also employ a fairly intricate lifting mechanism. Typically, four sets of cables, pulleys and motors are required to raise and lower the lift platform. The cables perform the actual lifting and separate and distinct reduction means, which include gears and/or pulleys, provide the mechanical advantage required to produce the necessary lifting torque. Such structure is typically complex and expensive.
Conventional boat lifts also exhibit a number of safety problems. Most lifts are driven by an electric motor. Various parts of the lift, which are often metallic or otherwise electrically conductive, tend to frequently and repeatedly contact the water. In many cases, the conductive lift components are not adequately insulated from the drive motor and other electrical parts of the mechanism. This may result in a short circuit and a dangerous risk of electrocution. Cable driven boat lifts also experience broken cables, which can cause serious injury to a person in the vicinity of the boat lift.
Most standard boat lifts simply raise an vessel out of the water and lower the vessel into the water. Known lift platforms typically lack the ability to turn or otherwise adjust the position of the vessel after it has been raised. We have determined that it would be quite advantageous to be able to rotate a lifted vessel so that it can be moved conveniently onto an adjacent dock or other dry surface besides the boat slip. Such a feature would be particularly beneficial for personal watercraft and other small vessels.
Most known boat lifts do not take full advantage of the adjacent piling or support to bear the lift load. Indeed some known products utilize a relatively small base that supports the lift platform in a cantilevered manner. These types of lifts often exhibit less than satisfactory strength and durability. Typically they are limited to lifting fairly light loads. The lift components tend to shift and sag over time.